Effects of antisense hsp27 gene expression in osteosarcoma cells

Analysis of HSP27 and the Autophagy Marker LC3B+ Puncta Following Preoperative Chemotherapy Identifies High-Risk Osteosarcoma Patients

Chemotherapy-induced autophagy is a proposed mechanism of chemoresistance and potential therapeutic target in osteosarcoma. We evaluated heat shock protein 27 (HSP27) and autophagy-related proteins as predictors of pathologic treatment response and prognostic markers among osteosarcoma patients who received standard chemotherapy. We analyzed 394 tumor specimens (pre-treatment, post-treatment, and metastases) from 260 osteosarcoma patients by immunohistochemistry for cytoplasmic light chain 3B (LC3B)-positive puncta, sequestosome 1 (SQSTM1), high mobility group box 1 (HMGB1), and HSP27 expression. The staining percentage and intensity for each marker were scored and the extent to which marker expression was correlated with pathologic response, relapse-free survival (RFS), and overall survival (OS) was assessed. LCB3+ puncta in post-treatment primary tumors (50%) and metastases (67%) was significantly higher than in pre-treatment biopsy specimens (30%; P = 0.023 and <0.001). Among 215 patients with localized osteosarcoma, both pre-treatment [multivariate hazard ratio (HR), 26.7; 95% confidence interval (CI), 1.47-484; P = 0.026] and post-treatment HSP27 expression (multivariate HR, 1.85; 95% CI, 1.03-3.33; P = 0.039) were associated with worse OS. Lack of LC3B+ puncta at resection was an independent poor prognostic marker in both univariate (HR, 1.78; 95% CI, 1.05-3.03; P = 0.034) and multivariate models (HR, 1.75; 95% CI, 1.01-3.04; P = 0.045). Patients with LC3B+/HSP27- tumors at resection had the best 10-year OS (75%) whereas patients with LC3B-/HSP27+ tumors had the worst 10-year survival (25%). Neither HSP27 expression nor the presence of LCB3+ puncta was correlated with pathologic treatment response. Our findings establish HSP27 expression and LC3B+ puncta as independent prognostic markers in osteosarcoma patients receiving standard chemotherapy and support further investigation into strategies targeting HSP27 or modulating autophagy in osteosarcoma treatment. Mol Cancer Ther; 17(6); 1315-23. ©2018 AACR.

Overexpression of murine small heat shock protein HSP25 interferes with chondrocyte differentiation and decreases cell adhesion

Although multiple functions for the small heat shock protein HSP25 have been proposed, its specific role during developmental and differentiation processes is not known. Cartilage is one of the tissues in which HSP25 is specifically and highly expressed during development. C1 cells, able to form aggregates in vitro, can be induced to differentiate into chondrocytes. In this study, we generated two stable transfected clones overexpressing HSP25 at two different levels. Cell morphology and growth rate were modified in both clones, although the actin content and distribution did not seem to be altered. Overexpressing clones had more difficulties in coalescing, leading to smaller aggregates and they did not differentiate into chondrocytes. Subsequently, these aggregates tended to dissociate into loose masses of dying cells. The strength of all these effects was directly correlated to the level of HSP25 overexpression. These data suggest that overexpressing HSP25 decreases cellular adhesion and interferes with chondrocyte differentiation.